Utilization of a rapid DNA-based assay for molecular verification of channel catfish, blue catfish, F1 hybrid, and backcross offspring at serveral life stages

Authors: Waldbieser, Geoffrey - Geoff; Bosworth, Brian

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/2007
Publication Date: 10/13/2008
Citation: Waldbieser, G.C., Bosworth, B.G. 2008. Utilization of a rapid DNA-based assay for molecular verification of channel catfish, blue catfish, F1 hybrid, and backcross offspring at serveral life stages. North American Journal of Aquaculture. 70:388-395.

Interpretive Summary: The F1 hybrid offspring of channel catfish, Ictalurus punctatus, females mated with blue catfish, I. furcatus, males contain many desirable traits for commercial production such as enhanced growth and increased survivability. Although at a low efficiency, hybrids can be produced by pond spawning, but hybrid catfish cannot always be readily distinguished from channel catfish, especially at early life stages. The present research was designed to produce a rapid DNA-based test for the identification of hybrid catfish. The test demonstrated our ability to differentiate tissues from blue and channel catfish, and detect their F1 hybrid offspring. We were also able to detect matings of F1 broodstock with blue or channel catfish females. The DNA preparation technique provided sufficient genomic DNA to test all life stages, from 1 day after fertilization to a cooked fillet. The results from this assay were available as soon as 24 h after receipt of sample. This assay will be useful for management of hybrid populations and post-harvest detection of hybrid catfish products.

Technical Abstract: The F1 hybrid offspring of channel catfish, Ictalurus punctatus, females mated with blue catfish, I. furcatus, males contain many desirable traits for commercial production such as enhanced growth and increased survivability. Although at a low efficiency, hybrids can be produced by pond spawning, but hybrid catfish cannot always be readily distinguished from channel catfish, especially at early life stages. The present research was designed to produce a rapid DNA-based test for the identification of hybrid catfish. Channel and blue catfish genomic regions were PCR-amplified using common primers for the follistatin (Fst) and hepcidin antimicrobial protein (Hamp) genes, and fragment length polymorphisms between the two species caused by ancestral insertions/deletions were resolved by agarose electrophoresis. The Fst amplicons were 399 and 348 bp while the Hamp amplicons were 262 and 222 bp from blue and channel catfish, respectively. The mitochondrial cytochrome c oxidase I gene (Mtco1) was also differentially amplified from each species using species-specific primers, thus the maternal parent species could be determined. The DNA preparation technique provided sufficient genomic DNA to test all life stages. The PCR products were successfully amplified from genomic DNA isolated from embryos at one, two, or five days after fertilization, from fry two days after hatching, from blood and barbels of juveniles and adults, and from fresh, frozen, and cooked fillet samples. The results from this assay were available as soon as 24 h after receipt of sample. This assay will be useful for management of hybrid populations and post-harvest detection of hybrid catfish products.